1. Field of the Invention
The invention relates to fuel injectors principly for the injection of fuel into the combustion chambers of diesel engines.
2. Discussion of the Related Art
Injectors are known in which the means for intensifying the pressure of fuel destined to be injected is carried on the injector body the advantage being that failure of any part of the intensifier including the controls therefor does not necessitate a dismantling of a whole hydraulic/fuel system and allows quick replacement of a faulty part. In certain cases as for instance in the system shown in U.S. Pat. Re. No. 33270 the benefits include total containment of very highly pressurised fuel within an injector assembly. Such injectors are usually inserted into a bore in the cylinder head so that a nozzle just protrudes into a combustion space formed when the piston reaches the top of its stroke. Such a combustion space can be an antechamber formed in the cylinder head or it can be a bowl formed in the crown of the piston. The antechamber type of combustion system is called an indirect injection system and the bowl-in-the-piston is called a direct injection system. It is well known that the direct injection system is a more efficient system because air and gases do not have to pass through a constriction, as in the indirect injection system and hence more air can be fed into it in a given time. In the search for methods of allowing more air into the direct injection combustion chamber of a diesel engine cylinder multiple inlet valves are becoming commonly employed. Whilst, in the case of a cylinder head having one inlet and one exhaust valve per cylinder the injector bore can be made in the side of the cylinder head where there is plenty of room, for an injector in a cylinder head which carries for instance two inlet and two exhaust valves there is very little room for an injector except in the space at the centre of the four valves. This necessitates that the injector shall project vertically from the top of the cylinder head. Problems consequent on the adoption of this arrangement are a) that the injector assembly is too tall and b) it interferes with the valve gear which of necessity must occupy the space.